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Core i7-8700K Review: Coffee Lake Brews A Great Gaming CPU

The Z370 Chipset & Graphics

The Z370 Chipset

Much to the dismay of enthusiasts everywhere, you can't buy a Coffee Lake-based CPU and drop it into the fancy Z270 motherboard you may have purchased a few months ago. Instead, you'll have to pony up for a 300-series motherboard. You also can't bring your Skylake or Kaby Lake processor over to a Z370-based platform, even though both sides employ LGA 1151 interfaces.

Intel makes more money selling CPUs than chipsets, so creating an upgrade path would have made sense. But the company tells us that it needed optimized memory trace routing to support DDR4-2666, and it also improved power delivery to support six-core models. It also beefed up package power delivery for overclocking.

According to Intel's specification sheet, the increased package power delivery consists of 18 pins repurposed to VCC (previously designated as reserve pins). There are also changes to the socket that reassign behaviors to some pins, such as swapping Normal Open (NO) and Normal Closed (NC) settings. Intel also improved power delivery to the graphics engine, and although the specific changes there remain undefined, that might improve HD Graphics overclocking.

The changes mean upgrading to Z370 is a technical necessity, rather than planned obsolescence. Regardless, though, AMD's planned support for Socket AM4 through 2020 makes Intel's Z370 chipset requirement appear all the more painful.

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CPU-based I/O remains unchanged from Kaby Lake; you still get 16 lanes of PCIe 3.0. Again, though, the whole platform supports up to 40 lanes. The extra 24 originate from the PCH, stuck behind a four-lane DMI 3.0 connection that links the core logic and CPU. As you might imagine, this PCIe-like interconnect can become a bottleneck if enough devices (like M.2 SSDs) are working behind it.

The 22nm Z370 chipset is rated at 6W, and is mostly identical to Z270. It offers up to 10 USB 2.0, 14 USB 3.0, and six SATA 6Gb/s ports. Intel added support for Thunderbolt 3, but hasn't provided much detail on the implementation. Z370 also retains support for Intel Optane Memory. Even the ME version 11 is listed similarly on Intel's ARK, though we do know that Z370's Management Engine doesn't allow Kaby Lake processors to boot on the platform. Two memory channels support up to two DIMMs per channel and a maximum of 64GB. Intel does not support ECC on any of its models (compared to AMD, which does allow motherboard vendors to enable ECC support).

Intel offers a few unique benefits to enthusiasts, such as the XTU (Extreme Tuning Utility) and support for XMP 2.0. The Performance Tuning Protection Plan is also available, which covers damage from overclocking. The price for the warranty plan varies per SKU, and Intel hasn't provided a detailed breakdown for Coffee Lake yet. We aren't aware of any AMD-equivalent coverage.

Intel UHD Graphics 630

Intel will have an optimized graphics driver soon after launch, but we don't see any significant improvements (beyond HDCP 2.2 support for DP 1.2a) to the Gen 9 LP (Low Power) engine. We still get subslices with eight EUs each (totaling 24 EUs in a GT2 configuration), accelerated slightly by a 50 MHz maximum frequency increase across the board.

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The biggest change comes from Intel's marketing department, which "upgraded" the High Definition (HD) Graphics 630 brand to Ultra High Definition (UHD) Graphics 630. Apparently, that means the company supports the same legacy VP8 and AVC codecs, HEVC 10-bit decode/encode, VP9 8/10-bit decode, VP9 8-bit encode (no support for VP9 10-bit encode), HDR, and Wide Color Gamut features. The processors now come in 6+2 (i5 and i7) and 4+2 (i3) configurations.


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Paul Alcorn is the Deputy Managing Editor for Tom's Hardware US. He writes news and reviews on CPUs, storage and enterprise hardware.